Self-contained servomechanism



Feb. 10, 1970 F- VAN BUSKIRK 3, 5,

SELF- CONTAINED SERVOMECHANI SM Filed March 19, 1968 2 Sheets-Sheet 1FIG. '2 T w I5 ll 3 l5 s3 26 22 I3 38 as 1 l2 M f 25 36 4| INVENTOR.LYMAN F. Van: BUSKIRK ROY MILLER ATTORNEY.

Feb. 10, 1970 L. F. VAN BUSKIRK 3,495,108

SELF-CONTAINED SERVOMECHANISM Filed March 19, 1968 2 Sheets-Sheet aAMPLIFIER FIG. 4.

IN VEN '1 0R. LYMAN F. VqN BUSKIRK ROY MILLER ATTORNEY.

United States Patent SELF-CONTAINED SERVOMECHANISM Lyman F. Buskirk,Ridgecrest, Calif., assignor to the United States of America asrepresented by the Secretary of the Navy r 4 Filed Mar. 19, 1968, Ser.No. 714,247

' Int. Cl. H02k 11/00 U.S. Cl. 310-68 1 Claim ABSTRACT OF THE DISCLOSUREA modular amplifier circuit is included in the housing of a synchroreceiver to provide a unitary package. The housing is designed toprovide easy access to the circuit module without disturbing the wiring.

BACKGROUND OF THE INVENTION The present invention relates to a devicefor the positioning of one shaft in response to the angular positioningof another in an accurately controlled ratio. More specifically, theinvention relates to a direct drive generatortransformer servo-systemarranged in a unitary package along with a module containing thenecessary electrical circuitry.

Prior devices of this type have suffered from numerous disadvantages,for example, (1) the electrical components required space outside of theservomechanism housing or (2) the electrical components wereinaccessibly contained in a housing made larger to accommodate thecomponents.

The present invention incorporates the electrical circuitry in an easilyreplaceable module fitted into the available space in a conventionalservomechanism by modification of a portion thereof to provide a heatsink mounting for the components of the module. The electronic modulemay be easily inspected by removal of a cupshaped cover withoutdisturbing the connections. The motor generator according to theinvention also may include a tachometer in conjunction with the motorand, in a preferred embodiment includes a reduction gearing between themotor and the generator.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS FIG. 1 is adiagrammatic view of a motor generator servomechanism according to theinvention;

FIG. 2 is a planned view of a servomechanism with parts broken away andin cross section to illustrate the arrangement of parts;

FIG. 3 is a cross sectional view taken along line 3-3 of FIG. 2;

FIG. 3A is a cross sectional view similar to FIG. 3 showing amodification of the drive mechanism;

FIG. 3B is a similar view showing yet a second modification of the drivemechanism; and

FIG. 4 is a diagrammatic representation of the invention illustratingtypical electrical circuitry.

DETAILED DESCRIPTION OF THE INVENTION As shown in FIG. 1 theservomechanism comprises a control transformer 11 having an output shaft12. The control transformer 11 is connected to a drive mechanism 15 bymeans of connecting shaft 18. The drive mechanism 15 is preferably areduction gearing as will be more fully described in relation to FIG. 2.The coupling 15 is connected to a motor 14 and tachometer 16 by means ofshaft 30, the end 19 of which may be splined to fit into a complementarysplined portion of gearing 15. The power supply for the servomechanismis indicated at 13 as being inside the modified servo housing 17.

A more detailed description of the servomechanism 10 is possible byreferring to FIG. 2 wherein housing 17 is ShOWn composed of severalinterfitting parts. One part 33 of housing 17 is provided with a flange36 which acts as a carrier for the electronic component module includingthe power supply 13. Since the part 33 and flange 36 are of metal, theportion 36 acts as a heat sink for the components as necessary. Themember 33 is also adapted to receive a cup-shaped housing member 41which acts as a cover for motor 14 and the power supply 13. Cup 41 isprovided at its outer end with a plurality of terminals indicatedgenerally at 39 and 40 and the connecting conductors 38 are long enoughto allow removal of the cup 41 without disturbing the internalconnections.

Although the motor 14 and the control transformer 11 may be directlyconnected, the device according to the present invention contemplatesthe use of a reduction gearing 15 which may be advantageously in theform of a harmonic drive. For example, as shown in FIG. 2, the motorshaft 19 has a carrier 24 fastened thereto by a pin 25. Carrier 24 has aplurality of rollers 26 on the periphery thereof which are retained inplace by shaft 31. A flexible gear 22 is fastened to the housing at 23and has a flange portion 21 which overlies the rollers 26 of the carrier24. At the points where the rollers 26 contact the flexible gear 22, theflexible gear 22 is deformed so that the external teeth of a gear 20(see FIG. 3), gear 20 is fastened to the input shaft 18 of the controltransformer as by a pin 27.

Turning now to FIG. 3 it may be seen that, if gear 20 be provided with200 teeth and gear 21 be provided with 198 teeth, when the carrier 24 isrotated in the direction of arrow 32, the gear 20 will then rotate inthe same direction (arrow 34) at a speed reduced by a ratio of 100.

An even greater gear reduction may be accomplished by the use of aplanetary system as shown in FIG. 3B wherein a modified shaft 19' isfrictionally engaged with three rollers 28 to provide a planetary systemcausing fiexible gear 21 to engage the gear 20 in three places. Becauseof the planetary arrangement of the input gearing, however, the rollers28 will move around the flexible gear 21 at a much slower rate than didthe rollers 26 of FIG. 3.

FIG. 3A shows a further modification of the harmonic gear drive in whicha modified shaft 19" has an oval shape and is grooved to retain ballbearings 29 in contact with the flexible gear 21. This arrangementaccomplishes the same result as the two roller system shown in FIG. 3.

FIG. 4 shows a circuit diagram in which leads S S and S represent theinput from a conventional synchro transmitter operatively connected tocontrol transformer 11. In response to the signals received from S S andS an error signal is generated in coil 42. The error signal is fed intoamplifier 13 which in turn energizes center I tapped coil 43. It shouldbe noted that coils 45 and 46 are always energized by AC main lines Rand R thus two phase AC motor 14 will turn in response to the errorsignal generated from coil 42. As two-phase AC motor 14 turns outputshaft 30, which is connected to tachometer 16, a current is generated incoil 44 which cancels the error signal generated by coil 42.Simultaneously, twophase AC motor 14 causes shaft 19 to turn drive 15and shaft 18. Shaft 18 in turn causes shaft 12 to turn so that theangular displacement of control transformer 11 returns to a zero errorposition where coil 42 no longer generates an error signal and thesystem returns to its stable state. It is further noted that the systemmay operate without the use of a tachometer 16. In this case the errorsignal generated by coil 42 will drive coil 43 and amplifier 13 causingtwo-phase AC motor 14 to operate shaft 19 to turn drive 15 and shaft 18to cause shaft 12 to coil 42. The advantage of tachometer 16 is that itpr o vide's additional -stalaility to "the'system by generating a seconderror signal in coi1f 44 which helps to stabilize amplifier 13.

Obviously many modifications and variations of the present invention arepossible in the light of the above teachings. It is therefore to beunderstood that ,Within the scope of the appended claim the inventionmay be practiced otherwise than as specifically described. I

The invention described herein may be manufactured and used by or forthe Government of the United States of America for governmental purposesWithout the payment of any' royalties thereon or therefor.

What is claimed is: 1. In a synchro receiver including; a controltransformer, a drive motor, and a drive coupling between said motor andsaid control transformer; the improvement comprising:

an enclosing housing including; a cylindrical main body portion, and acylindrical cup shaped end cover portion; said main body portionincluding a hollow cylindrical solid metal segment having oppositelyextending first and second axial flanges; said flanges respectivelyproviding means for attaching said segment to said main body and meansforming an annular shelf between said ive motorandsaidendcover; saidshelf forming, with said cover portion, a toroidal cavity surroundingsaid drive motor; and a toroidal electronics module, including powersupply means for said"receiver, mounted on said sli'elfs'otl'iat,-"allnecessa'iy electronics is included "within said housing,said shelf acts as heat sink for "electronics"components and inspectionof said electronicsmodule may be made by removing said cup; shapede'nd'co'ver without disturbing internal electrical connections.

References 'Cited UNITED STATES PATENTS 2,383,669 8/1945 Moore 310-6843,114,094 12/1963 Lee 310-68 3,170,079 2/1965 Jaeschke 31068 3,225,23212/1965 Turley 310 3,299,303 1/1967 Newill 31066 3,329,841 7/1967 Binder31068 3,250,929 5/1966 Maier 310-68 3,378,708 4/1968 Baker 3l066 I DMILLER, Primary Examiner US. Cl. X.R.

